Breasts and butts have served as the main appeal of Keijo‘s highly anticipated debut, a series which focuses around well-endowed women smacking each other with their naughty parts – certainly leaving many in stitches over how seriously the anime takes itself.

I always assumed this was something young women in Japan did for fun on beach vacations, like Suikawari. The earliest reference to it ive seeen in media was in Dead or Alive Xtreme 2 but I doubt it invented the idea...